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More details on the Ekaterinburg fire

In the last week, there have been two very interestingreports with additional information on the fire that seriously damaged the Ekaterinburg strategic nuclear submarine back in December. All the reports seem to agree that the submarine’s nuclear missiles and torpedoes had not been offloaded prior to the start of the repair, which meant that there had been a serious risk of a torpedo explosion while the fire burned.

But let’s start at the beginning. The reports indicate that the submarine came to Rosliakovo for a routine inspection, during which it was decided that damage to a cowling that covers the submarine’s sonar. This covering had been damaged either when the submarine was docking, or earlier in the summer or fall, depending on the report. In order to fix the cowling, an opening was made in the outer hull. The fire began during the repair (at 3:45pm Moscow time on December 29) as the result of sparks igniting wooden scaffolding. From the scaffolding, the fire spread to the rubber soundproofing covering that is located between the outer and inner hull. This covering supposedly becomes flammable only at very high temperatures, but once on fire it is very difficult to extinguish. The fire spread in the space between the two hulls, a location that is narrow and filled with various equipment, factors that increased the difficulty of fighting the fire. Three hours after the fire began, flames continued to shoot up to a height of 15-20 meters.

Those in charge at the site early on had the idea to submerge the floating dock in which the submarine was located, but the process was complicated by the presence of the Admiral Kulakov destroyer in the same dock. If the dock was submerged too far, the interior of the ship would be flooded. The Kommersant article that discusses this issue does not really address the question of how this was resolved, though it implies that the dock was partially submerged so that seawater could reach the submarine and extinguish the fire without rising so high as to flood the Kulakov. Afterwards, the fire was mostly brought under control, though it was not fully extinguished until 6:20pm on December 30, almost 27 hours after it began.

Numerous sources agree that both the submarine’s nuclear missiles and its torpedoes had not been offloaded prior to the inspection. The reports indicate that regulations do not require that the missiles be offloaded in this circumstance, but that the torpedoes should be. According to Novaia Gazeta, the base commander allowed the Ekaterinburg to enter the dock without offloading the torpedoes. Kommersant notes that this happens fairly frequently in order to avoid delays.

The torpedoes were located in the first compartment, only 40 meters from the fire. Here’s a picture of the front of the submarine:

The crew quickly realized the danger that extreme heat just on the other side of the inner hull might cause the torpedoes to explode. Since the hydraulic systems for torpedo removal were not functioning, they risked their lives to manually remove the torpedoes from the first compartment. According to Novaia Gazeta, three torpedoes were removed in this way. Had the torpedoes exploded, dozens of crew and firefighters would have been killed. Depending on the number of torpedoes affected, the authors of the Kommersant article raise the possibility that the explosion could have destroyed the floating dock and the Admiral Kulakov and might have led to radioactive contamination from the nuclear missiles or the two nuclear reactors onboard. I have no way of judging how serious that threat was, but whether or not it was real, a torpedo explosion would have certainly led to panic not just in Roslyakovo but also in the nearby cities of Severomorsk and Murmansk, which have a total population of almost 400,000 people. You can see the locations on the map below, from the Kommersant article.

Finally, let me turn to the consequences for the future of the submarine. This topic is addressed extensively in the Novaia Gazeta article. The good news is that according to Dmitry Rogozin the repairs will cost only 500 million rubles — half of the initially announced estimate. The article goes on to argue, however, that it is unlikely that the submarine will be able to submerge to significant depths in the future because the high temperatures sustained by the inner hull in the front section of the submarine may have compromised its strength. The author says that unless the entire front compartment is replaced, the submarine will only be able to submerge to limited depths without risking the lives of its crew.

I am sure that the Ekaterinburg’s first cruise after the repairs are completed will receive a great deal of attention. Given the potential consequences of a problem, hopefully no one will be cutting any corners.

Craig, in general, I don’t take anything said by Rogozin too seriously and haven’t in years. You may recall my recent post about his statement on submarine and aircraft carrier production. But in the absence of other information, we may as well note it as the government’s official position. In this case, I don’t have any specific information or knowledge that would discredit his statement.

I don’t know what kind of fuel load these reactors got and what kind of burnup they are at for the moment and how long they had been shut down before the fire, but if the sub carries 64 warheads the amount of plutonium in these must be half a tonne or so. Plutonium is not very radioactive, it is not very mobile in the environment and it’s only dangerous if inhaled or ingested. I don’t think contamination caused by damage to the nuclear weapons if it were to happen would be any major issue. It certainly can’t be compared to Chernobyl, as some have suggested. The latter contained some 190 tonnes of highly active material.

What about the possibility of contamination from the reactors? Anyway, I think the real threat would have been not so much the actual contamination, but the panic in nearby cities due to the perceived threat of contamination. Between the history of being lied to about Chernobyl and the recent events in Japan, I think the level of fear about radioactive contamination among Russians is quite high (not that it’s particularly low everywhere else…).

There is little publicly availible information about russian and soviet naval reactors, particulary later generation reactors. But most reactors are of the PWR type, including all operating reactors. Early generations used uraniumoxide fuel, while later reactors are using uranium alloy fuel. The fuel load range from from 30 to possibly as high as 200 kg U235, with modern reactors probably more closer to the latter than the former. Enrichment is said to be between 5 and 90% where a lower enrichment means more total uranium in the reactor for a given amount of U235. But it’s not the uranium that poses the radiation threat but the fission products produced when the reactor operate. Fission products build up as the burnup of the fuel increase, but they also decay with time. So the amount of contamination possible will depend on how much fission products the reactor contains at the time of the accident and how much is released into the environment where a release to the atmosphere is the major concern.

So far however, despite a number of accidents involving nuclear naval reactors release of radioactivity have been limited to the area around the vessels. For nearby cities fear of radiation is probably a greater concern than radiation itself.